RE: Black spots in Pt./Pd.

Bob,

Thanks for the informative reply.

I have now figured out that the problem was indeed the Lenox paper,
but it was not caused by the paper itself, or by the chemistry, but
by the way i coated the paper. The thing is, I was doing some 4X5
tests and the small 1" Richeson that I normally use for this is not
to be found, so I used instead a small 1" foam brush. Well, the
surface of the Lexox paper abrades *very* easily and it turns out
that the abrasion is the cause of the spots. The other papers that I
use have a harder surface and the foam brush did not cause the same
problem.

Have another small Richeon on the way so will wait to do any more
tests on Lenox until it arrives.

Sandy

>DEAR SANDY,
> My 3 cents...
> I have never found any problem with Lennox so I feel that is a low
>probability. What I DID find is that I have to clean the necks of my Ferric
>Oxalate dropper bottles and the inside of the dropper cap EVERY TIME before
>use. The crust of desiccated FO on them can fall into the solution as fine
>clumps or crystals and create black spots upon development. I had black
>spots on my prints using Lennox, Cranes Platinotype, and COT before I
>started doing this and I have never had any spots since!
> If you don't use droppers look for some place where the FO can dry and
>crystallize as the source of trouble.
> Some suggest that, if your metal solutions aren't warm enough
>you can get
>precipitates that can cause similar problems but, living in the tropics, I
>don't have that problem Some suggest that roller paper trimmers emit shards
>of iron or steel that can cause the same spots but I use a roller trimmer
>and have never had a problem with any of the papers above.
>
> Please check my website: http://www.bobkiss.com/
>
>-----Original Message-----
>From: Sandy King [mailto:sanking@clemson.edu]
>Sent: Tuesday, August 09, 2005 11:57 AM
>To: alt-photo-process-l@sask.usask.ca
>Subject: Black spots in Pt./Pd.
>
>
>Another Pt./Pd.question.
>
>I have not done any Pt./Pd.printing in about 6-8 months and when I
>began trying to calibrate my materials again I ran into a problem
>that I have not seen before, small black spots on the print that
>appear during development.
>
>The chemistry that I am using 1 part of 25% ferric oxalate plus 1
>part of 20% palladium chloride. The solutions are clear and are
>giving very good Dmax, even though they were mixed several months ago.
>
>The paper is Lenox, which I have not previously used for Pt./Pd. printing
>
>Does this sound like a paper issue, chemistry issue, or some type of
>contamination I am not understanding.
>
>Sandy
Received on Tue Aug 9 11:17:14 2005